關於iOS 6 部分UIViewController 轉屏問題

最近做一個項目 需要在UINavigationController下部分UIViewController 支持轉屏功能。蒐集了一下iOS 關於轉屏的API:

// Applications should use supportedInterfaceOrientations and/or shouldAutorotate..
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation NS_DEPRECATED_IOS(2_0, 6_0);

// New Autorotation support.
- (BOOL)shouldAutorotate NS_AVAILABLE_IOS(6_0);
- (NSUInteger)supportedInterfaceOrientations NS_AVAILABLE_IOS(6_0);
// Returns interface orientation masks.
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation NS_AVAILABLE_IOS(6_0)

根據以往的經驗，在iOS6以下的系統中，我們只需要實現：

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation 

這個方法，然後在不同的UIViewController 實現不同的轉屏方向：

// Note that UIInterfaceOrientationLandscapeLeft is equal to UIDeviceOrientationLandscapeRight (and vice versa).
// This is because rotating the device to the left requires rotating the content to the right.
typedef NS_ENUM(NSInteger, UIInterfaceOrientation) {
    UIInterfaceOrientationPortrait           = UIDeviceOrientationPortrait,
    UIInterfaceOrientationPortraitUpsideDown = UIDeviceOrientationPortraitUpsideDown,
    UIInterfaceOrientationLandscapeLeft      = UIDeviceOrientationLandscapeRight,
    UIInterfaceOrientationLandscapeRight     = UIDeviceOrientationLandscapeLeft
};

注意：UINavigationController 需要在RootViewController中實現該方法才起作用；UITabBarController同理。

而到了iOS 6.0及以上的系統，該方法已經過期，同樣需要轉屏的話需要現實一下API:

// New Autorotation support.
- (BOOL)shouldAutorotate NS_AVAILABLE_IOS(6_0);
- (NSUInteger)supportedInterfaceOrientations NS_AVAILABLE_IOS(6_0);

同樣需要在UINavigationController 或者 UITabBarController的RootViewController中實現；

但然後在需要轉屏的UIViewController 轉成與之前UIViewController 轉屏方向不同的情況下後退就會出現問題；

必須採用API：

- (void)presentViewController:(UIViewController *)viewControllerToPresent animated: (BOOL)flag completion:(void (^)(void))completion NS_AVAILABLE_IOS(5_0);

做到轉屏退出以後還是原來的UIViewController 維持原來的轉屏方向；

如果想做到無縫UINavigationViewController 的push & pop效果的話：

參考以下代碼:

push:

__block PhotoViewController *photoBrowser = [[PhotoViewController alloc] initWithDelegate:self];
    photoBrowser.displayActionButton = YES;
    photoBrowser.isCustom = YES;
    photoBrowser.galleryItem = myGalleryList_;
    
    if([[[UIDevice currentDevice] systemVersion] floatValue] > 5.9){
        BlankViewController *blank =  [[BlankViewController alloc] init];
        UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:blank];
       
        id vController = [[self.navigationController viewControllers] lastObject];
        if (vController != self){
            [self.navigationController popViewControllerAnimated:NO];
        }
        [self presentViewController:nav animated:NO completion:^{
            [nav pushViewController:photoBrowser animated:YES];
            [self setHidesBottomBarWhenPushed:YES];
            [self.navigationController pushViewController:blank animated:NO];
        }];
    }else{
        [self.navigationController pushViewController:photoBrowser animated:YES];
    }

pop:

    if ([[[UIDevice currentDevice] systemVersion] floatValue] > 5.9){
        if (UIInterfaceOrientationIsLandscape(self.interfaceOrientation)){
            [(UINavigationController *)[(AppDelegate *)fccsDelegate myTabBar].selectedViewController popViewControllerAnimated:NO];
            [self dismissViewControllerAnimated:YES completion:^{
            }];
        }else{
            [self dismissViewControllerAnimated:NO completion:^{
                [(UINavigationController *)[(AppDelegate *)fccsDelegate myTabBar].selectedViewController popViewControllerAnimated:YES];
            }];
        }
    } else {
        [self.navigationController popViewControllerAnimated:YES];
    }